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Re: Completly shearing a building (also answer to perforatedshearwalls)

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In a message dated 9/13/1999 9:20:33 PM Pacific Daylight Time, BD2PE(--nospam--at)aol.com 
writes:

<< Dennis,
 
 I have been trying to just lurk here in the background but can not.  Does it 
 really matter?  Do you really believe that the addiion of shear at the areas 
 that were not included in your design will reduce the strength of your 
 building?  How many buildings have been built with no engineering throuhgout 
 this country with out and engineer and they are performing more than 
 adequately?  I think sometimes we as engineers over estimate our importance.
 
 Just my thoughts.
 
 Brian Dunagan, P.E.
 
 P.S. Where are the bodies? >>


Brian, to a degree I agree with you. However, this was not the intent of my 
message. My post was to hypothesis the intent of the strict code compliance 
that we are to follow based compared to the reality of what will be 
constructed in the field.
I not only agree with you, but would personally be willing to state that 
compliance to past codes without conformance with torsion design (rigid 
diaphragm analysis) is more than sufficient as long as the structure is 
properly detailed and tied together.

My issue was to ask the community (mostly those from seismology if listening) 
how we should address the differences occuring from the design numbers to 
what will be constructed in the field. If the structure is entirely sheathed, 
while designed for only necessary shear resistance, then, theoretically, the 
balance of distribution of force will change based on the uncalculated 
stiffness of the walls that are not specifically designed to resist shear. 
These walls, however, will or should come into play at some point of 
deflection of the designated walls - but were not considered in the original 
design.

Are we expected to recalculate the structure? Who is to pay? Are we liable 
for "any" damage that an expert witness claims to be caused by the 
redistribution of shear caused by construction? Are we liable for changes in 
stiffness if the contractor decides it is less costly to place nails at 3" on 
center for all walls rather than try and follow a schedule?

In a cynical way I am agreeing with your comments "where are the bodies".  
After two custom homes, I am convinced that this is not a good methodology.

Dennis